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  • 1
    Electronic Resource
    Electronic Resource
    The actions of ryanodine on Ca2+-activated conductances in rat cultured DRG neurones; evidence for Ca2+-induced Ca2+ release (1999)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 81-91 
    Details
    ISSN: 1432-1912
    Keywords: Key words Ryanodine ; CICR ; Calcium-activated ; chloride currents ; Action potential after-depolarizations ; Niflumic acid ; Dantrolene ; Cultured sensory neurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The whole-cell recording technique was used to investigate the actions of a calcium release channel ligand, ryanodine, on calcium-activated chloride conductances, and to evaluate ryanodine-sensitive Ca2+-induced Ca2+ release from intracellular stores in cultured neonatal rat DRG neurones. The aim of the project was to use ryanodine as a pharmacological tool to evaluate calcium-induced calcium release in the cell bodies of cultured DRG neurones. Action potential after-depolarizations were attenuated by extracellular application of the chloride channel blocker, niflumic acid (10 µM), and by ryanodine (10 µM); these actions occurred without concurrent changes in evoked action potentials. Ryanodine and caffeine (10 mM) activated calcium-dependent conductances and the responses to ryanodine were attenuated by depletion of caffeine-sensitive Ca2+ stores. The current clamp data were complicated by changes in potassium conductances so studies were carried out under voltage clamp and voltage-activated calcium currents and calcium-activated chloride and non-selective cation currents were isolated pharmacologically. Ryanodine (10 µM) evoked delayed, inward, calcium-activated non-selective cation and chloride currents which reversed close to 0 mV and were attenuated by N-methyl-d-glucamine, niflumic acid and dantrolene. Consistent with actions on action potential after-depolarizations, niflumic acid (10 µM) and ryanodine (10 µM) attenuated calcium-activated chloride currents evoked by calcium entry through voltage-activated calcium channels. Niflumic acid and ryanodine had no effects on voltage-activated calcium currents evoked from a holding potential of –90 mV by voltage step commands to 0 mV. In conclusion calcium-activated chloride conductances appear to be activated in part by calcium released from ryanodine-sensitive stores, and significant calcium-induced calcium release may occur locally in cell bodies of DRG neurones as a result of calcium entry through voltage-activated channels during an action potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005335
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Photoactivation of intracellular guanosine triphosphate analogues reduces the amplitude and slows the kinetics of voltage-activated calcium channel currents in sensory neurones (1988)
    Springer
    Pflügers Archiv 411 (1988), S. 628-636 
    Details
    ISSN: 1432-2013
    Keywords: Guanine nucleotide analogue ; Calcium current ; Flash photolysis ; Guanine nucleotide binding protein ; dorsal root ganglion neurone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of guanine nucleotide analogues on calcium channel currents in cultured rat dorsal root ganglion neurones has been studied using a technique in which the rate of diffusion of the analogues to their site of action is by-passed by photochemical release of the analogues within the neurones. The 1(2-nitrophenyl)ethyl P3-ester derivatives of guanosine 5′-0(3-thio)triphosphate (caged GTP-γ-S) and 5′-guanylylimidodiphosphate (caged GMP-PNP) were synthesised and found to be completely photolysable by light, yielding free GTP-γ-S and GMP-PNP. Calcium channel currents were recorded using the whole cell patch technique and either caged GTP-γ-S or caged GMP-PNP (2 mM) were included in the patch pipette. Stable currents were recorded for 5–10 min, and a single pulse of 300–350 nm irradiation was directed using a liquid light guide onto the recording dish. Calcium channel currents were then recorded every 30–120 s following photochemical release of approximately 20μM GTP-gg-S. The peak calcium channel current was reduced by about 70% with a slow time course [t 1/2 1.5±0.2 min (mean±SEM);n=5]. The transient component of the peak current was usually completely abolished, whereas the sustained current measured at the end of the 100 ms depolarising pulse was less affected. Qualitatively similar effects were observed on photolysis of caged GMP-PNP. These results suggest that the channels underlying the transient and the sustained components of the whole cell current may be differentially molulated by GTP analogues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580858
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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